Device and method for polishing or abrading products

ABSTRACT

A device for polishing or abrading products (M), includes: a polishing element ( 1 ) provided with an operating surface ( 4 ) designed to perform a polishing or sanding movement, preferably a circular or orbital movement; 
     motor elements ( 13 ) operatively connected to the polishing element ( 1 ) for impressing on the operating surface ( 4 ) the polishing movement; 
     one or more air ducts ( 3 ) extending from an inlet opening ( 5 ), which communicates with a source ( 7 ) of a flow of treated air, for example dried air, gaseous nitrogen, or modified air rich in nitrogen, to one or more outlets ( 6 ) of the flow distributed in an area corresponding to the operating surface ( 4 ); and
         elements ( 8 ) for regulating the temperature of the flow of treated air at a value comprised between −5° C. and +20° C.

SECTOR OF THE INVENTION

The invention relates to the sector of polishing and/or sanding ofproducts, and in particular of polishing of metal substrates, forexample made of steel or brass, or else of painted products.

More in particular, the invention regards the sector of polishing ofpainted substrates using pads, whether with rotary or orbital motion,for example of the type used in vehicle-body repair or in themotor-vehicle industry in general or again in the industry of wood andplastic.

STATE OF THE ART

There have been known and marketed for some time polishing devices,rotary and random-orbital polishers actuated by electric motors orpneumatic turbines, which use a pad that is set in rotation by a tooland that is passed over the product possibly in combination withabrasive polishing pastes or creams.

However, known systems are not satisfactory since their use entailsprogressive and/or violent rise in temperature, which is dangerous forthe surface being treated, on account of the operating friction betweenthe polishing pad chosen and the surface of the product to be polished.

Moreover, in the case of polishing of wooden surfaces, the air tends tocause clogging with the moisture present therein, whereas nitrogen isanhydrous and dries the surface during polishing, thus preventing thisdrawback.

A further drawback is represented by the considerable interference thatis caused by the relative humidity present in the operating environmentand by the high temperatures of the environment, for example in summerperiods or in given localities, in addition to the dust in suspension inthe polishing environments.

In the case of painted products, the rise in temperature of thematerials (plastic material, aluminium, ferrous materials, products madeof glossy lacquered wood, etc.) inevitably leads, in fact, to seriousproblems of loss of elasticity of the underlying film of paint causingpattern formation, lesions and cracking, but also phenomena of halos andso-called holograms, i.e., marks left by traditional random-orbitalpolishers on the polished products.

PURPOSE OF THE INVENTION

A first purpose of the present invention is hence to propose a polishingdevice and a polishing method that will be free from the drawbacksreferred to above and will enable improvement of the polishing quality,at the time same reducing power consumption and the processing timenecessary.

SUMMARY OF THE INVENTION

The above and further purposes have been achieved with a device and amethod according to one or more of the annexed claims, which envisagethe use of treated air, preferably cold dry air obtained, for example,with a dryer with cooling cycle or by absorption (indicatively with dewpoint comprised between −20° C. and +10° C.), or even more preferablynitrogen or else modified air rich in nitrogen, heat-conditioned at atemperature indicatively comprised between −5° C. and +20° C.

A first advantage is represented by the fact that the treated air isheat-conditioned at various temperatures that can be selected accordingto the environment of use and/or to the type of the substrates to bepolished, and is injected between the fibres of wool or other materials(for example, sponge) commonly used in polishing pads. In this way, infact, the surface of contact between the pad and the product remainscold even at high speeds, and the risk of damage to the polishedsurface, and in particular to the film of paint, is extremely reduced.

A further advantage is represented by the fact that a considerablesaving of time is obtained, owing to a higher rate of execution of thepolishing process, and hence marked reduction above all for long jobsthat involve several hours of application and expenditure of a greatamount of physical energy.

Yet a further advantage is represented by the fact that nitrogen is aninert gas, free from humidity and any type of impurity, which sensiblyreduces the risk of damage to the polished surface, and in particular tothe film of paint.

Yet a further advantage is represented by the fact that use of nitrogenenables a saving in energy, roughly up to 40% less, as compared to theuse of traditional systems.

A further advantage is represented by the fact that it is possible torespect safety values as regards the temperature of the surface treated,since the random-orbital movements with cooling obtained with treatedair prevent said values from being exceeded, without the risk of“burning” the transparency and jeopardizing the brilliancy defined inthe quality specifications of the paints.

A further advantage is represented by the fact that the use ofheat-conditioned treated air enables complete exploitation of thesurface of contact of the pad, whereas in traditional systems, onaccount of the high temperatures that are dangerous for the surfacebeing treated, it is necessary to keep the pad inclined with respect tothe working surface, and the operator necessarily uses on average just40% of the potential useful surface of contact.

A further advantage is represented by the fact that there is obtained apainted surface without holograms, i.e., without the marks left bytraditional random-orbital polishers. The use of heat-conditionedtreated air in a random-orbital polisher does not, in fact, createholograms and guarantees a high quality of the finished surface, even ina single pass, removing completely scratches, halos, streaks, andoxidation.

LIST OF THE DRAWINGS

The above and further advantages will be better understood by any personskilled in the branch from the ensuing description and from the annexeddrawings, which are provided by way of non-limiting example and inwhich:

FIG. 1 shows a manual polishing device according to the invention;

FIG. 1a shows a front view of the disk of the device of FIG. 1;

FIG. 2 shows a polishing apparatus according to the invention; and

FIG. 3 is a schematic representation of a device and an apparatusaccording to the invention.

DETAILED DESCRIPTION

With reference to the attached drawings, there now follows a descriptionof a device for polishing and/or sanding products M, in particular butin a non-limiting way, painted products.

The device comprises a disk 1 provided with an operating surface 4,which, in use, assumes a circular or orbital movement obtained withappropriate means 13, for example an electric or pneumatic motor,capable of impressing the polishing motion on the operating surface 4.

Preferably, removably applied on the surface 4 of the disk is apolishing pad 12 permeable to a flow of gas.

According to the invention, the device comprises a source 7 of a flow oftreated air, for example cooled dry air, or nitrogen, or nitrogen-richmodified air, and one or more air ducts 3 extending from an inletopening 5, which communicates with the source 7 by means of ducts 22, toone or more outlets 6 for the flow of treated air, located on theoperating polishing surface 4, for example in areas corresponding toholes and/or a gap created between the pad and a suction hood 20.

Advantageously, the invention envisages means 8 for regulating thetemperature and/or pressure of said flow of treated air.

Preferably, the regulation means are provided for regulating thetemperature at a value comprised between −5° C. and +20° C. and thepressure of the flow of treated air at a value comprised between 1 barand 5 bar.

In the embodiment illustrated, the source 7 and the regulation means 8are integrated in a unit 9 for delivering a flow of treated air, forexample nitrogen-rich modified air produced by means of hollow-fibreseparation membranes or by means of a system with PSA (Pressure-SwingAbsorption) molecular sieves.

Advantageously, the unit 9 comprises a second outlet 17 for a flow of apressurized carrier fluid suitable for painting, for example a flow oftreated air as described above, which is in turn possibly regulated inpressure and/or temperature, said outlet communicating via ducts 23 withan air-painting device 10. With this solution, one and the same supplyunit 9 can be used both for polishing and for painting the product M.

In order to improve the efficiency of the polishing and/or paintingoperation, there may moreover be provided an ionization unit 11 providedfor charging said flow of treated air with an overall positive,negative, or neutral charge, which is for example integrated in the unit9.

Preferably, the means 13 for impressing the motion on the disk 1comprise an electric motor 13 housed within a casing 14 provided withmanual grip 16, extending inside which are the air ducts 3 thatcommunicate with the source of treated air.

In a different embodiment, the means 13 comprise a pneumatic motor 21,the movement of which is supplied by a pressurized airflow.

Advantageously, the pressurized flow that supplies the pneumatic motor21 may be formed by a part of a flow of treated air used for thepolishing operation.

In use, to carry out polishing of a painted product M, the operatorsimply has to start the motor drive of the polishing element 1, enabledelivery of a flow of treated air to the outlet holes 7, and bring theoperating surface 4 up to the product M possibly after application of alayer of abrasive cream or paste of the type commonly used forpolishing.

Thanks to the invention, the flow of treated air that exits from theholes 6 carries out a continuous cleaning of the surface being polishedwith a gas free from humidity and impurities and at the time sameimproves the treatment of the paint and prevents the heat generated bycontact between the operating surface 4 and the product M from inducingdeformation.

The effect of compensation of the heat generated by the friction isfurther improved by the use of heat-conditioning of the flow of treatedair, which may be regulated both on the basis of the type of polishedmaterial and on the basis of the ambient conditions.

The present invention has been described according to preferredembodiments, but equivalent variants may be conceived, without therebydeparting from the sphere of protection of the invention.

1. A device for polishing or abrading products (M), comprising: apolishing element (1) provided with an operating surface (4) designed toperform a polishing or sanding movement, preferably a circular ororbital movement; and motor means (13) operatively connected to saidelement (1) for impressing on the operating surface (4) said polishingmovement, wherein the device further comprises: one or more air ducts(3) extending from an inlet opening (5), which communicates with asource (7) of a flow of treated air, for example dried air, gaseousnitrogen, or modified air rich in nitrogen, to one or more outlets (6)of said flow distributed in an area corresponding to said operatingsurface (4); and means (8) for regulating the temperature of said flowof treated air at a value comprised between −5° C. and +20° C.
 2. Thedevice according to claim 1, further comprising means for regulating thepressure of said flow of treated air at a value comprised between 1 barand 5 bar.
 3. The device according to claim 1, wherein said polishingelement (1) comprises a disk provided with a polishing pad (12)permeable to said flow of treated air that can be removably applied onsaid operating surface (4).
 4. The device according to claim 1, whereinsaid means (13) provided for impressing on the operating surface of saiddisk a circular or orbital motion comprise an electric motor (13) housedwithin a casing (14) provided with a manual grip (16).
 5. The deviceaccording to claim 1, wherein said means (13) provided for impressing onthe operating surface of said disk a circular or orbital motion comprisea pneumatic motor (21) housed within a casing (14) provided with amanual grip (16), the movement of which is supplied by a pressurizedairflow.
 6. The device according to claim 5, wherein the movement ofsaid pneumatic motor (21) is supplied by a part of said flow of treatedair.
 7. The device according to claim 6, wherein said air ducts (3) areprovided within said casing (14).
 8. The device according to claim 1,wherein said operating surface (4) is able to perform a circular motion,and said outlet (6) of the flow of treated air comprises holes oroutlets arranged concentrically with respect to the axis of rotation. 9.A polishing apparatus comprising a device according to claim 1, and aunit (9) for supply of a flow of nitrogen-rich modified air produced byseparation, preferably with hollow-fibre or molecular-sieve separationmembranes, wherein said source (7) and said regulation means (8) areintegrated in the unit (9).
 10. The apparatus according to claim 9,wherein said unit (9) comprises a second outlet (17) for a flow ofnitrogen-rich modified air, which communicates with an air paintingdevice (10).
 11. The apparatus according to claim 9, comprising anionization unit (11) provided for charging said flow of treated air witha positive, negative, or neutral overall charge.
 12. A method forpolishing products by means of a device comprising: a disk (1) providedwith an operating surface (4) designed to perform a polishing movement,for example a circular or orbital movement; and means (13) operativelyconnected to said disk for impressing on the operating surface (4) apolishing or sanding motion, for example a circular or orbital motion,wherein the method comprises the steps of: driving said operatingsurface (4) in rotation; sending on said operating surface (4) a flow oftreated air, for example nitrogen or modified air rich in nitrogen at aregulated temperature; and setting at least one portion of said rotatingoperating surface (4) in contact with a painted surface (15) of aproduct (M).
 13. The method according to claim 12, wherein said products(M) are painted products.
 14. The apparatus according to claim 10,comprising an ionization unit (11) provided for charging said flow oftreated air with a positive, negative, or neutral overall charge.